The invention concerns electrodes for measuring the level of milk in flowmeters and positioned together in a holder of a non-conductive material that extends tight through the bottom of the flowmeter with their active surfaces vertically separated.
Electrodes of this type are known for example from U.S. Pat. No. 4,386,523. Reacting to changes in the level of milk in the flowmeter, they activate a valve body that opens or closes an outlet in the bottom of the flowmeter in accordance with the level. When the level of milk, which always changes between the two electrodes, is employed to compute the flow of milk, the electrodes must emit a signal whenever the milk is at precisely the same level. The electrodes in the known flowmeter are annular. It has been demonstrated that such electrodes do not always react to precisely the same level because their triggering point or triggering height is not precisely defined in that a certain section of the surface must be contacted by the liquid before a signal can be emitted. Furthermore, organic, inorganic and mineral constituents of the milk can form deposits on the surface of the electrodes and vary their transitional resistance and accordingly the triggering height. Electrodes of the aforesaid type also require complicated holders.
Straight electrodes partly enclosed in insulation have also been employed. A ring of liquid can be left, as a result of adhesion or cohesion for example, at the transition between the insulated and uninsulated surface and change the triggering height. These electrodes are also subject to deposits that contaminate the results.